let distance point1 point2 = 
 	let r = 6371.0 and pi = 4.0 *. atan 1.0 in
	((acos ((sin (point1#get_latitude *. pi /. 180.0))*.(sin (point2#get_latitude*. pi /. 180.0))+.(cos (point1#get_latitude*. pi /. 180.0))*.(cos (point2#get_latitude *. pi /. 180.0))*.(cos ((point2#get_longitude*. pi /. 180.0)-.(point1#get_longitude*. pi /. 180.0))))) *. r) *. 0.62137
